implement basic keyboard firmware for my 40% ortho prototype, along with debug display info

src/display.rs

@@ -0,0 +1,85 @@
+use embedded_graphics::{
+    mono_font::{MonoTextStyleBuilder, ascii::FONT_6X10},
+    pixelcolor::BinaryColor,
+    prelude::Point,
+    text::{Baseline, Text},
+    draw_target::DrawTarget,
+    Drawable,
+};
+use ssd1306::{prelude::*, I2CDisplayInterface, Ssd1306, mode::BufferedGraphicsMode};
+use embassy_rp::i2c::I2c;
+use core::fmt::Write;
+
+/// Display type encapsulating the I2C interface, its size and graphics mode
+pub type Display = Ssd1306<
+    I2CInterface<I2c<'static, embassy_rp::peripherals::I2C0, embassy_rp::i2c::Async>>,
+    DisplaySize128x32,
+    BufferedGraphicsMode<DisplaySize128x32>
+>;
+
+/// Function that initializes the display with given settings
+pub fn init_display(bus: I2c<'static, embassy_rp::peripherals::I2C0, embassy_rp::i2c::Async>) -> Option<Display> {
+    let interface = I2CDisplayInterface::new(bus);
+    let mut display = Ssd1306::new(
+        interface,
+        DisplaySize128x32,
+        DisplayRotation::Rotate180,
+    )
+    .into_buffered_graphics_mode();
+
+    match display.init() {
+        Ok(_) => Some(display),
+        Err(_) => None,
+    }
+}
+
+/// Temp function which updates the display with currently pressed keys
+pub fn update_display(
+    display: &mut Option<Display>,
+    pressed_keys: &[(usize, usize, crate::keymap::KeyCode)],
+) -> Option<()> {
+    if let Some(display) = display {
+        display.clear(BinaryColor::Off).ok()?;
+    
+        let text_style = MonoTextStyleBuilder::new()
+            .font(&FONT_6X10)
+            .text_color(BinaryColor::On)
+            .build();
+    
+        if pressed_keys.is_empty() {
+            Text::with_baseline("No keys", Point::zero(), text_style, Baseline::Top)
+                .draw(display)
+                .ok()?;
+        } else {
+            let mut y_pos = 0;
+            for (row_idx, col_idx, keycode) in pressed_keys.iter().take(3) {
+                let mut msg = heapless::String::<32>::new();
+                write!(&mut msg, "R{}C{}: 0x{:02X}", row_idx, col_idx, keycode.as_u8()).ok();
+    
+                Text::with_baseline(&msg, Point::new(0, y_pos), text_style, Baseline::Top)
+                    .draw(display)
+                    .ok()?;
+    
+                y_pos += 10;
+            }
+        }
+    
+        display.flush().ok()?;
+        Some(())
+    } else {
+        None
+    }
+}
+
+/// Helper function to clear the display
+pub fn clear_display(
+    display: &mut Option<Display>,
+) -> Option<()> {
+    if let Some(display) = display {
+        display.clear(BinaryColor::Off).ok()?;
+        display.flush().ok()?;
+        Some(())
+    } else {
+        None
+    }
+}